Speech, language, and swallowing difficulties can result from a variety of causes including stroke, brain injury/deterioration, developmental delays/disorders, learning disabilities, cerebral palsy, cleft palate, voice pathology, mental retardation, hearing loss, or emotional problems, and the difficulties can be either congenital, developmental, or acquired.
Speech-language pathologists assess, diagnose, treat, and help to prevent disorders related to speech, language, cognitive-communication, voice, swallowing, and fluency. Treatment modalities may include range of motion and isometric exercises of oral mechanisms. In typical clinical practice, a patient performs isometric exercises against a tongue depressor that is held by a clinician.
As a result, diagnostic baseline data and therapeutic progress is measured by a subjective and qualitative assessment of force against the tongue depressor held by the clinician, or more specifically, the speech pathologist. These types of measurements are inaccurate because the perception of the exerted force against the tongue depressor is inexact and may vary from session to session. Furthermore, patients may be treated by different speech pathologists and thus the overall progress of the patient is subjectively assed by several clinicians.
Although the potential to obtain a reliable measure of tongue strength in multiple directions is described by U.S. Pat. No. 4,697,601 (Durke), devices such as those described by Durke remain too expensive and too cumbersome for clinical use. Durke describes a device using strain gauges to measure tongue force simultaneously in three directions by having an individual push against a tongue cup. A bifurcated tooth plate is fastened to the device, and serves as a means of patient registration (the physical connection between the patient and the fixed point against which measurements are taken). Otherwise, without the bifurcated tooth plate, if the therapist were simply to try and hold the device in place while the patient pushes against it then the therapist influence could easily be as great, or greater, than the effect tying to be measured.
Patient registration is a primary differentiation point between devices designed to measure tongue strength. Early attempts, such as those described by U.S. Pat. No. 4,585,012 (Rumburg), describe table mounted devices where an individual places their chin into a chin rest or a device strapped to a patient's head.
At the other end of the spectrum is the IOWA Oral Performance Instrument described by U.S. Pat. No. 5,119,831 (Robin), which provides no fixed means of patient registration. The clinician simply holds onto a tube placed into the patient's mouth, which has a pressure sensing bulb at its extreme end, that the patient compresses against another body part.
The IOWA Oral Performance Instrument is one of the few devices to be commercially available and has been studied by numerous authors. In clinical practice, it is most often used to measure the pressure an individual can exert against the roof (hard palate) of the patient's mouth. The measurement bulb may also be adhered to a lateral tongue bulb holder. Once adhered, the patient bites down on the holder to create a registration point for side-to-side (lateral) and sticking out the tongue (protrusion) measurements. Therefore, for lateral and protrusion measurements, the patient is required to not only push against the bulb but to simultaneously bite down to keep the device in place, just as would be required by the device described by Durke.
In order to get around the requirement that a patient simultaneously bite and push, U.S. Pat. No. 5,954,973 (Staehlin) and U.S. Pat. No. 6,702,765 (Robbins) both employ a mouth piece that substantially conforms to the patient's anatomy as a means of patient registration. U.S. Pat. No. 6,511,441 (Wakumoto) goes so far as to attach electrodes directly to the patient's hard palate. These customized mouth pieces are expensive to produce and expensive and time consuming for the therapist to employ in daily practice.
Therefore, present devices lack a simple and efficient means of providing patient registration that does not require the patient to simultaneously bite and push.
Unfortunately, a lack of an efficient means of patient registration is not the only deficiency of the devices described above. In almost all the devices, a patient is simply pushing against a “wall” without any sense of movement or work being done. This lack of movement leads to increased patient training needs (especially for those with tongue desensitization), and lack of motivation. It simply is not a fun and enjoyable exercise to repeatedly push against a wall.
Not only is there a lack of a motivational factor in the devices described above, the relevance of simply focusing on peak force (or duration that an individual can maintain 50% of the peak force, referred to as endurance), has been consistently questioned in literature and at clinical conferences.
The Journal of Speech and Hearing Disorders Vol. 52, pages 367-387 November 1987 (Kent) suggests that maximum performance measures may not be relevant to speech because “speaking under ordinary circumstances does not tax the performance capabilities of the speech system.” Although it has been more than 20 years since Kent called for a “second generation of speech production measures,” the focus of most devices on peak measurement fails to meet the need of providing measurable objective exercise in the range actually utilized in speech production.
In addition, speech production can be effected by repeated use (saying words). However, there is little clinical correlation between real life fatigue and a patient's endurance based upon how long they can push their tongue against a wall. Additional measures are still needed.
U.S. Pat. No. 7,238,145 (Robbins) describes a means of adjusting exercise resistance. However, the adjustment is based on discrete (fixed) settings, rather than continuous (fractional values within a range). Additionally, there is limited feedback indicating exercise completion and difficulty in patient registration.